Gebix is a FreeBSD-based operating system that will be available for both x86 and ARM as of version 0.7 Release Candidate 1. It will sacrifice most of the legacy support to transition to new or recent alternatives.

Quarn OS is a free operating system, written from scratch. It is not based on any existing operating system, because implementing the same things in the different way is not the main goal of Quarn OS Project. Currently, Quarn OS run only on x86 machines.

FreeOS/1 is a Free, Open Source, FreeDOS based Free and Open Source Alternative OS, with open source Microsoft Windows compatibility using HXDOSExtender KernelEx,and ReactOS source code. FreeOS/1 will include new technologies and will be easy to use

I have developed and tested a small 32-bits Kernel running on i386. I want to share it to this developers community. The kernel is developed in Assebly Language and it have bootloader, multitask, etc, etc...

BNL OS is a free, modern operating system based on the design of Windows XP/2003.This is not a Linux based system, and shares none of the unix architecture. Please remember, this is in the development stage, and is not reccommended for everyday use.

The Danber project aims to create an operating system where both Windows and Linux programs can be run: it is a Windows NT based kernel, but with UNIX user mode compatibility. Support for both PE and ELF executable formats.

Fortress OS is an open source modern multitasking operating system. Intel IA-32 386 compatibility. Fortress is clean implemented from scratch. Fortress is still in early stage ( current state at the end of plan 2 ) and needs huge work.